Making A Mini AM Transmitter Better

The chances are that many of you will have made an FM “bug” style transmitter, a simple one-transistor oscillator usually driven by a small electret microphone. It’s also relatively straightforward to do the same for AM, and if you take a look through AliExpress you’ll find some modules which do just that. [Doz Television Workshop] has one, and he’s treated us to a thorough run-down of its design before addressing some of its shortcomings.

An AM transmitter is simple enough, in this case an oscillator and buffer driving a class C power amplifier. The modulation is applied by a transistor in series with the power amp, driven from an audio amplifier. Some attention has gone into the design of this one, with a proper output filter and plenty of room for tweaking to achieve proper levels and modulation density. There are some problems though — The modulator transistor is mounted upside down for the heatsink, and the frequency stability leaves something to be desired. [Doz] fixes the heatsink mounting and incorporates a DDS frequency synthesizer with an Arduino for control.

More after the break…

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Hackaday Links: January 26, 2025

Disappointing news this week for those longing for same-hour Amazon delivery as the retail giant tapped the brakes on its Prime Air drone deliveries. The pause is partially blamed on a December incident at the company’s Pendleton, Oregon test facility, where two MK30 delivery drones collided in midair during light rain conditions. A Bloomberg report states that the crash, which resulted in one of the drones catching fire on the ground, was due to a software error related to the weather. As a result, they decided to ground their entire fleet, which provides 60-minute delivery to test markets in Arizona and Texas, until a software update can be issued.

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The ESP32-C5, Finally Espressif Goes Dual-Band

The ESP32 series of microcontrollers have been with us for quite a few years now, providing a powerful processor and wireless connectivity for not a huge outlay. We’ve seen a bunch of versions over the years with both Tensilica and RISC-V cores, but so far the ones with radios have all only serviced 2.4 GHz WiFi. That’s about to change to include 5GHz with the new C5 variant though, and [Andreas Speiss] has been lucky enough to get his hands on a prototype dev kit

It’s very similar to the C6, which we’re already used to beyond the dual-band 2.4GHz and 5GHz radio from a software point of view. The C5 is so new that the company has yet to incorporate the new chip into the Arduino IDE. He shows it working and detecting both networks though, and speculates a little about its eventual marketing.

Interesting to us is the dual-band antenna, with branches for both frequencies on the same PCB. We’d be interested to see the real-world performance of this, and also whether they produce a version with separate outputs for each band. The full video is below the break. In the meantime, watch out for this chip appearing on the market.

It’s not the only Espresif chip we’re anticipating at the moment.

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A Waist Level Viewfinder For Not A Lot

Photographic accessories are often plagued by high prices, as photography is considered a rich man’s game. It doesn’t have to be that way though, and [Snappiness] is here to get you started on the route to cheaper kit with a waist-level viewfinder project.

If you’ve used a twin-lens reflex camera then you should be familiar with a waist level viewfinder, it’s a lens and mirror arrangement allowing the photographer to frame the shot looking down from above. Modern cameras often have no viewfinder, so this is aimed at digital compacts without flip-up screens.

It has three components, all available for relatively low prices, and mounted in a 3D printed case. There’s a prime lens, a mirror, and a Fresnel lens forming the part the photographer looks through. It’s a simple device, but still one which would cost a lot more off the shelf. The video is below the break.

It might interest you to know that this is not the first viewfinder project we’ve brought you for digital cameras.

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Schematic of quantum measurement basis on whiteboard

Shedding Light On Quantum Measurement With Calcite

Have you ever struggled with the concept of quantum measurement, feeling it’s unnecessarily abstract? You’re not alone. Enter this guide by [Mithuna] from Looking Glass Universe, where she circles back on the concept of  measurement basis in quantum mechanics using a rather simple piece of calcite crystal. We wrote about similar endeavours in reflection on Shanni Prutchi’s talk at the Hackaday SuperConference in 2015. If that memory got a bit dusty in your mind, here’s a quick course to make things click again.

In essence, calcite splits a beam of light into two dots based on polarization. By aligning filters and rotating angles, you can observe how light behaves when forced into ‘choices’. The dots you see are a direct representation of the light’s polarization states. Now this isn’t just a neat trick for photons; it’s a practical window into the probability-driven nature of quantum systems.

Even with just one photon passing through per second, the calcite setup demonstrates how light ‘chooses’ a path, revealing the probabilistic essence of quantum mechanics. Using common materials (laser pointers, polarizing filters, and calcite), anyone can reproduce this experiment at home.

If this sparks curiosity, explore Hackaday’s archives for quantum mechanics. Or just find yourself a good slice of calcite online, steal the laser pointer from your cat’s toy bin, and get going!

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Prompt Injection Tricks AI Into Downloading And Executing Malware

[wunderwuzzi] demonstrates a proof of concept in which a service that enables an AI to control a virtual computer (in this case, Anthropic’s Claude Computer Use) is made to download and execute a piece of malware that successfully connects to a command and control (C2) server. [wonderwuzzi] makes the reasonable case that such a system has therefore become a “ZombAI”. Here’s how it worked.

Referring to the malware as a “support tool” and embedding instructions into the body of the web page is what got the binary downloaded and executed, compromising the system.

After setting up a web page with a download link to the malicious binary, [wunderwuzzi] attempts to get Claude to download and run the malware. At first, Claude doesn’t bite. But that all changes when the content of the HTML page gets rewritten with instructions to download and execute the “Support Tool”. That new content gets interpreted as orders to follow; being essentially a form of prompt injection.

Claude dutifully downloads the malicious binary, then autonomously (and cleverly) locates the downloaded file and even uses chmod to make it executable before running it. The result? A compromised machine.

Now, just to be clear, Claude Computer Use is experimental and this sort of risk is absolutely and explicitly called out in Anthropic’s documentation. But what’s interesting here is that the methods used to convince Claude to compromise the system it’s using are essentially the same one might take to convince a person. Make something nefarious look innocent, and obfuscate the true source (and intent) of the directions. Watch it in action from beginning to end in a video, embedded just under the page break.

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A black box with the words "Steam BRICK" emblazoned in white and orange text. It sits on a grey surface with various electronic parts surrounding it.

Steam Brick Makes Your Steam Deck Headless

Handhelds are designed to be portable, but what if you need something smaller than OEM? The Steam Brick pulls basically everything off of a Steam Deck to make it as portable as possible.

[crastinator-pro] found they rarely used the controller or screen on their Steam Deck, and the form factor was too bulky to conveniently chuck into their bag, negating the advantage of owning a portable console. As to be expected from any self-respecting hacker, they did a couple quick tests with components unplugged then got to work with the rotary tool.

After excising the main board from its handheld bonds and trimming unnecessary bits from the aluminum frame around the mainboard, they designed a case that can be tossed in a bag without any special treatment. The case was printed in polycarbonate to better withstand the heat of the console running at full tilt, and the colorful details were added in PLA with a 3D pen.

We’ve discussed using a Steam Deck as a single-board computer before, but if you want to keep it in one piece, you could also get it setup in a slick keyboard case.